Waveguide window



Dec. 14, 1965 J. s. HICKEY, JR

WAVEGUIDE WINDOW Filed April 17, 1964 INVENTOR: JOHN s. HICKEY,JR. WW

HIS ATTORNEY.

United States Patent 3,223,950 WAVEGUIDE WINDOW John S. Hickey, Jr., Scotia, N.Y., assignor to General Electric Company, a corporation of New York Filed Apr. 17, 1964, Ser. No. 360,540 12 Claims. (Cl. 33398) This invention relates to diaelectric type windows for waveguide applications, and more particularly, to an improved method of providing such windows.

In many R.=F. (radio frequency) transmission applications it is often found necessary to pass electromagnetic wave energy through a waveguide having portions of its length subjected to different pressures. For example, it is a practice to isolate the vacuum portion of the electron tubes, used for generating or amplifying energy at high power levels at microwave frequencies, from the remainder of the system by means of a hermetically sealed dielectric window. These wave permeable gas tight windows have a multitude of physical configurations and chemical compositions. For example, such gas tight windows have various geometrical configurations and include such materials as mica, quartz, sapphire, various ceramics, and other dielectrics. These windows have a common problem relating to proper sealing of the dielectric to a metal frame in conjunction with critical dimensional tolerances. The occurrences of tolerance irregularities are accentuated by manufacturing methods which require close tolerance frame machining plus close tolerance dielectric window structure dimensions, and a further brazing procedure which has inherent heat strain problemsv Therefore, prior art window assemblies ordinarily require the use of elaborate fixtures and careful techniques to minimize errors. These methods and their associated processes add greatly to the overall cos-t of the windows, which is affected by the kind of production care that is necessary, by the number of loss items which result from such a process, and also by other manufacturing difficulties.

Accordingly, it is an object of this invention to provide an improved waveguide window.

It is another object of this invention to provide an improved parts assembly for a waveguide window.

It is a further object of this invention to provide an improved method of assembling a waveguide window.

It is a further object of this invention to provide an improved one-step brazing operation for .a waveguide window.

Brie-fly described, this invention, in one preferred form, includes the use of a pair of flanged opposed rim members in the form of metal stampings, which retain therebetween an edge-positioned dielectric window having a pair of opposed tapering ends. In a one-step brazing operation the pair of metal stampings are closely conformed by their dual nature to the edge of the dielectric window and are brazed together at the flanges and at the tapered ends of the window, while at the same time the dielectric window is brazed along its peripheral edge to the rim members.

This invention will be better understood when taken in connection with the following description and the drawings in which FIG. 1 is an isometric assembly view of one prefer-red embodiment of this invention;

FIG. 2 is an isometric exploded view of the assembly of FIG. 1;

FIG. 3 is an isometric view of a modification of the invention as illustrated in FIG. 1;

FIG. 4 is a further modification of the invention of FIG. 1.

Referring now to FIG. 1, there is shown in assembled ice isometric view one preferred form of a waveguide window 10 incorporating the teachings of the instant inven tion. In FIG. 1, window unit 10 includes a pair of pposed and similar rim or cover members 11 and 11. These rim members 11 and 11' as illustrated in FIG. 1 are dished or otherwise curved to provide, when placed in their opposed relationship, an elongated cross-sectional opening 12 to contain a dielectric window 13.

As illustrated in 'FIG. 2, wind-ow 13 is of substantially less axial length than the corresponding axial length of the rim members 11 and 11', so that the opening 12 need not be of identical configuration with window 13 along its entire length. It is preferred, however, to have the defined opening coextens-ively similar to the configuration of the window 13. While the cross-sectional illustration of the opening 12 may include various forms such as rectangular, polygonal, circular, ellipsoidal, and combination forms of both geometrically regular and irregular design, one preferred window 13 configuration is illustrated in FIG. 1 as an elongated hexagon. The elongated hexagonal opening 12 or window '13 is defined as a hexagon whose parallel sides are of a substantially greater length than the other sides. Rim members 11 and 11' each include an internal curvature or depression configuration which closely matches one-half of the elongated hexagon configuration taken along its longer axis. In order to join members 11 and 11 as an integral assembly, each of the members 11 and 11' includes laterally extending flanges 14 and 15 and 14' and 15' respectively, which are mutually engage-d as illustrated in FIG. 1. In operative relationship these flanges abut along a line which is parallel to the central or longitudinal axis of window 13.

It is an important feature of this invention that the window 13 be formed as an elongated body having tapered ends. It is desirable to have end surfaces which may be suitably bonded to a metal frame by a pair of directly opposed forces. Obviously, however, with a rectangular or square window an applied force is necessary at each surface to provide effective coextensive bonding. As may be well understood, coextensive bonding around a corner is also difficult. It has been discovered that the kind of bonding desired may be best practiced on elongated bodies, such as for example an elongated hexagon. In such a body no vertical walls are present which would require additional forces, no 90 corners are presented, and a pair of opposed suitably formed press su-r faces applies the required force to all surfaces. Other window configurations which may be employed in this invention to good advantage are those having the described tapering ends, these ends being defined by substantially intersecting arcs, lines, or combinations thereof, segments of circles, V sections, et cetera. Complementary engagement of the window 13 to the rim members is facilitated by the use of a pair of rim members which accommodate a greater tolerance and for this reason are applicable to all mentioned window configurations.

In order to provide suitable flanges for RF. connections, each of the rim members 11 and 11' is provided with an upturned flange 16 and 16' respectively extending in a direction generally parallel with the longer side of the hexagonal configuration of window 12, or transverse to flanges 14 and 15.

As best illustrated in the exploded View of FIG. 2, rim member 11' is disposed in an upwardly concave position to receive the dielectric material window 13 therein in close-fitting and confining relationship. Rim member -11 is also disposed to engage window 13 in close confining relationship and to abut rim 11' at flanges l4 and 15'. Window 13 is adapted to transmit electromagnetic wave energy therethrough from a face frontal surface 17 through a corresponding opposite surface 17' (not shown) a thickness of /2 wavelength. The wind-ow edge or periphery surface is illustrated as 18 and is employed as the bonding surface. As noted, the axial length of the window 13 is substantially less than the axial length of the rim members 11 and 11'. This arrangement provides better control over assembling errors or final attachment.

In order to provide proper sealing of the dielectric window material to the rim members, the dielectric window material may include intermediate sealing or bonding materials, for example in the form of shims, or be suitably coated with a sealing material. Such a coating 19, for example, may be applied in accordance with any of the known processes for metalizing the window material. If the window is of ceramic, the metalizing may advantageously include the manganese method which is disclosed in U.S. Patents 2,667,427 Nolte, and 2,667,432 Nolte, each assigned to the assignee of the instant invention. In accordance with the disclosed method of 2,667,427 Nolte, there is described a mixture of manganese and a powder selected from the group consisting of molybdenum, iron, tungsten, and nickel, but preferably consisting of molybdenum which is mixed with a quantity of elemental manganese and painted or sprayed on the surface to be metalized. The coated surface is then heated in a hydrogen atmosphere to a temperature on the order of about 1400 C. for a period of 5 to 15 minutes to provide a tightly adhering coating. This coating is thereafter utilized as a brazing surface.

Various alternate processes to the above-described manganese-molybdenum method may also be employed in the practice of this invention with good results. For example, in an additional process, the area to be metalized is painted or covered with powdered titanium hydride in a suitable carrier or binder and the parts assembled in the final position. A body of solder is placed in suitable position to melt and flow into contact with the coated area when it is melted. This assembly is heated in a vacuum to a temperature sufficient to dissociate the hydride and melt the solder. A method of soldering which may be used is described and claimed in U.S. Patent 2,570,248 Kelly, assigned to the same assignee as the present invention.

Referring again to FIG. 2, with the dielectric material suitably coated with a bonding material and resting securely in the dished rim member 11, the top or cover rim 11 is placed into juxtaposed position with rim 11 so that the combination of the rim members closely confines the hexagon configuration of the dielectric window 12. At this time the flanges 14 and 15 and 14' and 15' are also in engaged relationship as illustrated in FIG. 1. For the brazing operation a suitable brazing material may be placed on the internal surfaces of the flange members. The foregoing arrangement may be placed within a brazing fixture so that the mentioned parts may be suitably bonded together as described. This arrangement not only facilitates the manufacture of waveguide windows but also reduces the number of highly critical tolerances associated with former types of waveguides. For example, the close tolerances between a ceramic Window and a frame have been minimized in favor of these tolerances being shifted to the pair of metal rim members which are capable of absorbing a greater degree of irregularity. The brazing operation which bonds the flange members also provides increased coextensive bonding between the ceramic member and the rim members because the rim members are flexible to the extent that they are formed to and with the ceramic member.

The preferred elongated window body configuration substantially eliminates vertical, and near vertical, surfaces and their corresponding corners, since the tapered edge surfaces define wedge-like opposite ends, or tapered ends defined by a pair of intersecting surfaces, some small percentage of roundness of the edge being acceptable as a practical matter. These opposed tapered ends at the longer axis of elongated bodies are preferred forms of the invention as compared to rectangular or circular windows. Clamping fixtures are simplified and bonding forces are evenly distributed about the periphery of the window with a minimum number of parts or applied forces. The arrangement also provides that the brazing between the ceramic members and the rim members and also between the rim members may take place simultaneously with minimal error, and is a decided improvement in the waveguide window art.

In order to suitably join or attach the waveguide window unit 10 to a waveguide member, an attaching flange surface member 20 is provided as a transition member. Flange 20 as illustrated in FIG. 1 is usually of a rectangular section of sheet metal having a defined aperture therethrough which closely approximates the periphery of the waveguide unit 10 including the extending lateral flanges 14 and 15 and 14 and 15'. As can be seen in FIG. 1, flange 20 is slidably positioned over one end of the waveguide unit 10 and then brazed or welded into position. This brazing may also take place at the same time that other brazing of the parts of the waveguide unit 10 takes place.

With brazing material between the flanges of the rim elements and between the rim members and the attaching flange 20, and with a brazing material between the ceramic window and the rim members, the unit is suitably secured with a jig fixture as well known in the art and placed in a brazing furnace. With the brazing material so chosen that the brazing temperature for all parts becomes approximately the same, these brazing materials melt and flow between adjacent parts to provide hermetically sealed and rigid bonds. Thus with one heating step and a minimum of parts, four for example, an R.F. window construction is provided.

The waveguide window of this invention is not restrictive to the hexagonal configuration as described in FIG. 1, but is applicable to numerous other cross-sectional configurations. For example, referring now to FIG. 3, there is illustrated a ceramic waveguide unit 21 having the window 22 cross section of a general ellipsoid or more particularly a cross section which is defined by a pair of similar opposed intersecting lines or arcs. The corresponding rim members 23 and 24 are also illustrated and the assembly follows that assembly as described with relation to FIG. 1.

The modification of FIG. 4 includes additional blocks 25 and 25' of dielectric material which are bonded to the rim members 11 and 11 along the external surface which is opposite the internal bonding surface between window 13 and rims 11 and 11'. These blocks are preferably of the same or substantially the same material as window 13. Blocks 25 and 25' are also included in the simultaneous bonding process. The particular function of these blocks is more of a manufacturing expedient in that they provide a sandwich structure for the intermediate rim material, and thus control differential expansion and contraction characteristics to minimize the possibility of air leaks through the internal bond.

The objects of this invention are best carried out and optimum results obtained when this invention includes a rim member which is composed of two parts or rim elements, each of the rim elements having laterally extending flanges for joining purposes. An elongated window is edge-mounted in the rim members so that sealing of the rim members to each other occurs at tapered ends of the window and along a line which is transverse to the window.

While this invention has been described with reference to particular and exemplary embodiments thereof, it is to be understood that numerous changes can be made by those skilled in the art without actually departing from the invention as disclosed, and it is intended that the appended claims include all such equivalent variations as come within the true spirit and scope of the foregoing disclosure.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A waveguide window unit comprising in combination (a) a dielectric material window having opposed face surfaces adapted to transmit electromagnetic wave energy therethrough,

(b) said opposed face surfaces defining peripheral edge surfaces tapering toward each other to define at least one end,

(c) a pair of rim members about the said edge surfaces substantially in total contact therewith and conforming to the periphery of said window,

(d) each of said rim members having an outwardly turned flange member at an end thereof to define an abutting surface along the tapered end of said window,

(e) and bonding means between said window and said rim members and between said flange members to join said elements into an integral waveguide window unit.

2. The invention as recited in claim 1 wherein each face surface of said dielectric window defines a body member configuration having opposed tapering end portions.

3. The invention as recited in claim 1 wherein said face surfaces of said dielectric window each define an elongated configuration having opposed tapered ends.

4. The invention as recited in claim 1 wherein the said face surfaces of said dielectric window define a body member configuration having tapering V shaped end portions.

5. The invention as recited in claim 1 wherein the said face surfaces of said waveguide window define a hexagonal configuration with the two opposed parallel sides of greater length than the other sides.

6. The invention as recited in claim 1 wherein the tapered edge surfaces of said waveguide window substantially intersect at ends thereof.

7. The invention as recited in claim 1 wherein the cross-sectional configuration of said waveguide window is defined at least in part by a pair of equal opposed intersection arcs.

8. The invention as recited in claim 1 wherein each of said rim members includes a bent-up flange portion along an edge thereof transverse to the said lateral flange member.

9. A waveguide window unit comprising in combination (a) a dielectric material window having opposed face surfaces adapted to transmit electromagnetic wave energy therethrough,

(b) said opposed face surfaces defining peripheral edge surfaces tapering to define at least one tapered end,

() a pair of rim members about the said edge surface substantially in total contact therewith and conforming to the periphery of said window,

(d) each of said rim members having an outwardly turned flange member at an end thereof to define abutting parallel surfaces parallel to and coextensive the tapered ends of said window.

(e) and bonding means between said window and said rim members and between said flange members to join said elements into an integral waveguide window unit,

(f) and a further body of dielectric material bonded to said rim members externally thereof and along the bonding juncture of said window.

10. A waveguide window unit comprising in combination (a) a dielectric material window having opposed face surfaces adapted to transmit electromagnetic wave energy therethrough,

(b) said opposed face surfaces defining peripheral edge surfaces which taper at opposite ends of said win- 6 dow to provide substantially intersecting surface edges,

(0) a pair of rim members about the said edge surface substantially in total contact therewith and conforming to the periphery of said window,

(d) each of said rim members having an outwardly turned flange member at an end thereof to define abutting surfaces along the tapered ends of said window,

(e) bonding means between said window and said rim members and between said flange members to join said elements into an integral waveguide window unit,

(f) a transverse attaching flange at at least one end of said window,

(g) said transverse attaching flange having an aperture therein to receive said window and said rim flanges,

(h) and bonding means between said rims and said attaching flange for joining thereof.

11. A waveguide window unit comprising in combination (a) an elongated tapered ended dielectric material window having opposed frontal surfaces attached to transmit electromagnetic wave energy therethrough,

(b) said opposed frontal surfaces defining a peripheral transverse edge surface,

(c) said opposed surfaces having the form of an elongated hexagonal configuration,

(d) a pair of rim members coextensive with the said edge surface and substantially conforming to the periphery of said window,

(e) each of said rim members comprising a half-hexagonal configuration defined by a line of demarcation in the longer axis of said window,

(f) said rim members extending transversely substantially beyond said window edge surface,

(g) each of said rim members having an outwardly turned flange member at each lateral end thereof to define abutting surfaces parallel to the tapered end of said window,

(h) bonding means between said edge surface of said window and said rim members and between said flange members for joining said elements into an integral waveguide window unit,

(i) a flange surface member having an opening therein whose cross-sectional configuration corresponds to the cross-sectional configuration of said window for flange members,

(j) said flange surface member receiving one axial edge of said rim members within said opening,

(k) and bonding means between the periphery of said opening and said rim members for bonding therethrough.

12. A waveguide window unit comprising in combination (a) an elongated tapered ended dielectric material window having opposed frontal surfaces adapted to transmit electromagnetic wave energy therethrough,

(b) said opposed frontal surfaces defining a peripheral transverse edge surface,

(0) said opposed surfaces having the form of an elongated hexagonal configuration,

(d) a pair of rim members coextensive with the said edge surface and substantially conforming to the periphery of said window,

(e) each of said rim members comprising a half-hexagonal configuration defined by a line of demarcation in the longer axis of said window,

(f) said rim members extending transversely substantially beyond said window edge surface,

(g) each of said rim members having an outwardly turned flange member at each lateral end thereof to define abutting surfaces parallel to the tapered end of said window,

(h) bonding means between said edge surface of said window and said rim members and between said flange members for joining said elements into an integral waveguide window unit,

(i) a flange surface member having an opening therein whose cross-sectional configuration corresponds to the cross-sectional configuration of said window for flange members,

(j) said flange surface member receiving one axial edge of said rim members within said opening,

8 (k) bonding means between the periphery of said opening and said rim members for bonding therethrough, (l) and a further body of dielectric material bonded to said rim members externally thereof and along 5 the internal bonding juncture of said window to said rim members.

No references cited.

HERMAN KARL SAALBACH, Primary Examiner.

10 R. F. HUNT, Assistant Examiner. 

1. A WAVEGUIDE WINDOW UNIT COMPRISING IN COMBINATION (A) A DIELECTRIC MATERIAL WINDOW HAVING OPPOSED FACE SURFACES ADAPTED TO TRANSMIT ELECTROMAGNETIC WAVE ENERGY THERETHROUGH, (B) SAID OPPOSED FACE SURFACES DEFINING PERIPHERAL EDGE SURFACES TAPERING TOWARD EACH OTHER TO DEFINE AT LEAST ONE END, (C) A PAIR OF RIM MEMBERS ABOUT THE SAID EDGE SURFACES SUBSTANTIALLY IN TOTAL CONTACT THEREWITH AND CONFORMING TO THE PERIPHERY OF SAID WINDOW, (D) EACH OF SAID RIM MEMBERS HAVING AN OUTWARDLY TURNED FLANGE MEMBER AT AN END THEREOF TO DEFINE AN ABUTTING SURFACE ALONG THE TAPERED END OF SAID WINDOW, 